The subject matter disclosed herein generally relates to cooling flow in gas turbine engines and, more particularly, to forward facing tangential onboard injectors.
In gas turbine engines, tangential onboard injectors (TOBI) are used to direct cooling air toward a rotating disc that supports a plurality of turbine blades. The TOBI is configured to swirl secondary flow cooling air in a direction that is parallel to or along a direction of rotation of the rotating disc. Because of this, leakage flow into a primary or main gaspath that flows through the turbine section will be substantially parallel. That is, TOBI cooling air that leaks from the cooling areas below the gaspath are inserted into the gaspath in the same swirl direction as the rotating rotor.
Because the TOBI is located forward of or in front of the rotating disc, in an axial direction of a gas turbine engine, a vane in the gaspath will turn (swirl) the gaspath air in the same direction of the rotating rotor. Likewise, the leakage air in front of the blade that is swirled by the TOBI, enters the gaspath in the same tangential flow direction. So when the two flows (gaspath and leakage) mix with each other at the inner diameter of the gaspath, both flows are swirling in the same direction.
However, it may be advantageous to control the mixing flow of TOBI leakage flow, particularly as various new engine configurations are designed.